In industries with manufacturing processes involving fluids, numerous pumps and other rotary shaft devices are required for the transport and handling of fluids such as slurries and chemical solutions. The flushing water requirements of these seals for seal lubrication and radical or fugitive emission suppression greatly increased operational water requirements and increased the volumes of liquid wastes requiring treatment to remove environmental pollutants.
Our rotary seals are developed to solve these problems. These seals are believed to rely on mixed boundary asperity lubrication between a resilient seal member and a hard smooth surface of an opposed sealing member, the pressure at the contact surface between these two members being sufficient to minimize flow of liquid between their sealing faces. The normally high friction between such elastomeric materials and hard surfaces would appear to so severely limit the useful life of such seals that they would not be practical. One would expect that a significant flow of liquid lubricants would be required to reduce this friction.
We found that if the contact area of the resilient member was minimized, the resilient materials at the contact area were stress hardened, the polymeric components were aligned in a direction parallel to the hard sealing surface, and heat transfer elements were provided to remove heat from the sealing contact surfaces, the life of such seals was greatly extended and satisfy industrial requirements, without conventional thin film liquid lubrication. These "dry faced" seals required negligible flow of product for lubrication, unlike conventional mechanical seals. The liquid product in the stuffing box has a primary function of removing heat. Remaining heat is removed by conduction through the stationary sealing member.